The known cooling device takes the form of a crosscurrent heat exchanger with a number of groups of mutually parallel cooling channels and a number of groups of evaporating channels which are likewise mutually parallel and which run perpendicularly of the cooling channels. A group of cooling channels here adjoins in each case two groups of evaporating channels on either side, and vice versa, whereby as it were a layered structure of the heat exchanger is obtained.
The walls which form the partition between the cooling channels and the evaporating channels, and which thus serve for the transfer of heat (or cold) therebetween, are manufactured from a material which conducts heat very well, such as for instance aluminum. The walls of the evaporating channels, also including the walls forming the partition between the evaporating channels and the cooling channels, are all covered with a material which can retain moisture. Arranged above the evaporating channels are wetting means in the form of periodically operating sprayers which spray a quantity of water onto the walls with the moisture-retaining material.
In the known cooling device air for cooling, for instance ambient air, is drawn in by a fan and forced through the cooling channels. From the cooling channels the cooled air flows for instance to a space for ventilating. When leaving the cooling channels part of the air, for instance a third of the volume flow, is however separated from the main flow and guided to the evaporating channels. There, the cooled air flows along the moist walls, whereby moisture is evaporated and entrained in the airflow. Evaporation of the moisture results in a reduction of the temperature of the walls. Due to the good heat conduction of the transfer walls, this also results in a temperature decrease in the cooling channels, whereby the airflow is thus cooled.
Compared to for instance an air conditioning installation, this known cooling device on the basis of indirect evaporation has the advantage that cooling of the air requires only little power. This cooling device moreover has few moving parts, so that it can be manufactured and installed in simple manner and at low cost. In addition, no cold-generating agents are necessary.
Compared to direct evaporation coolers, the indirectly operating cooling device has the advantage that cooling of the air does not involve an increase of the air humidity. The supply of day cooled air results in a pleasant climate in the space cooled thereby. With such an indirectly operating cooling device the air can moreover be cooled to a lower temperature than would be possible with a direct evaporation cooler. Where the direct evaporation cooler cannot cool the air beyond the so-called “wet bulb” temperature, the indirectly operating evaporation cooler can cool the air to the so-called “dewpoint”, which is the reason the known cooling device is also referred to as a dewpoint cooler.